The Taumel type reclining device is a device in which an internal gear is provided on one of the seat cushion side and the seat back side, an external gear that has a smaller number of teeth than the internal gear and that is engaged with the internal gear is provided on the other of the seat cushion side and the seat back side. A position where the internal gear and the external gear engage is changed while one of the internal gear and the external gear eccentrically moves about a rotation axis of the other gear and thus a tilting angle of the seat back with respect to the seat cushion changes.
As illustrated in FIG. 13, a pair of a wedge (wedge-shaped member) 5 and a wedge (wedge-shaped member) 7 are arranged in an eccentric annular space between an internal surface of a circular hole 1a of an internal gear 1 and an external surface of a cylinder 3a of an external gear 3. The pair of the wedge 5 and the wedge 7 are biased by a spring 9 in a direction (direction indicated by an arrow A or an arrow B) in which the wedge is pushed into a narrow-width portion of the eccentric annular space.
A groove 5c and a groove 7c recessed with passing though in a rotation-axis direction are formed in wedge front end sides of the wedge 5 and the wedge 7.
The wedge 5 and the wedge 7 respectively press the internal surface of the circular hole 1a and the external surface of the cylinder 3a to bias the internal gear 1 and the external gear 3 in a direction in which an amount of eccentricity between rotation axes of both likely to increase. Then an internal tooth 1b of the internal gear 1 and an external tooth 3b of the external gear 3 are fully engaged with each other. Thus, the seat back is not tiled (locked state: a non-operating state).
An abutting surface 11a and an abutting surface 11c, or an abutting surface 11b and an abutting surface 11d of a striker (lock release member) 11 press a surface 5a and a surface 5b or a surface 7a and a surface 7b, which are on the wedge front end sides of the wedge 5 and the wedge 7, against an urging force of the spring 9 to press the wedge 5 or the wedge 7 in a direction (direction opposite to the direction into which the wedge is pushed which is a direction opposite to the arrow A direction or the arrow B direction) in which the wedge is pulled out. When, the striker 11 presses the wedge 5 or the wedge 7 to move, a pressing force to make the wedge 5 or the wedge 7 be in contact with the internal surface of the circular hole 1a or the external surface of the cylinder 3a decreases and, the engagement between the internal tooth 1b and the external tooth 3b is loosened. Thus, the seat back is in a state where the tilting is possible.
When the wedge 5 or the wedge 7 starts to move, the wedge 7 or the wedge 5 stops due to friction between the internal surface of the circular hole 1a and the external surface of the cylinder 3a. However, when one wedge moves in the direction in which the wedge is pulled out, due to an elastic repulsion force of the spring 9, the other wedge moves in the direction in which the wedge is pushed into the eccentric annular space. By repeating the operation, an engagement part changes and the seat back is tilted while retaining the state of eccentricity between the internal gear and the external gear (lock-released state: an operating state) (refer to Japanese Patent No. 5418197).